- #1
oldspice1212
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Homework Statement
The net force on the mass is the central force F(r) = -k(r-a). Find the potential energy U(r).
a is the spring of natural length and k is spring constant k.
Homework Equations
-dU/dx = F(x)
The Attempt at a Solution
[tex]F(r) = - \frac{ dU }{ dr } implies -k(r-a) = - \frac{ dU }{ dr }[/tex]
So I did this and then integrating both sides I got
[tex]\frac{ kr^2 }{ 2} - kar = U(r)[/tex] but this doesn't make much sense when I graph it out, as it gives me a parabola, and I would be expecting a asymptotic type function?